The present invention is related to a press-type bit-holding mechanism of a dental high-speed handset, in which the holder barrel and the push button can be more firmly located to more truly transmit the power. In addition, by means of pressing the push button, the bit can be conveniently extracted and replaced.
In general, the treatment of a dentist to a patient includes prosthesis of caries, grinding, etc. Various bits can be installed on a dental handset, such as an engine bur and a grinding head. Therefore, the handset is most frequently used instrument among all the dental implements. In curing work, the bit is placed in a patient's oral cavity and driven. Therefore, it is necessary to precisely and firmly locate the bit. In case the bit loosens when a dentist works, the dentist will put the patient's life in great danger.
In the conventional bit locating mechanism, a holder barrel is installed in a hollow rotary shaft. The thickness of the holder barrel is tapered from one end to the other end. The bit is held in the holder barrel. The holder barrel is tightly fitted in the hollow rotary shaft to fix the bit. A push button is fitted in the hollow rotary shaft and drivingly connected with the holder barrel via a linking section, whereby the holder barrel is rotatable along with the rotary shaft. By means of pressing the push button, the thicker end of the holder barrel can be retracted from the hollow rotary shaft to detach the bit from the rotary shaft.
According to the above arrangement, the holder barrel is simply drivingly connected with the push button via the linking section. The connecting strength is insufficient so that it is possible that the holder barrel unexpectedly drops out of the rotary shaft. As a result, the bit can be hardly firmly located. Therefore, due to vibration in operation, the bit and the holder barrel are easy to wear. In order to more firmly lock the bit with the holder barrel, it is necessary to enhance the precision of the dimension of the holder barrel and the bit and promote the quality of the material thereof. This inevitably will increase the cost.